Here is the text of the NIST sp800-63b Digital Identity Guidelines.
Microsoft used to do that. I made a password in the late 90’s for a we service and I found out that it truncated my password when they made it after it warned my my password was too long when I tried to log in. It truncated at 16 characters.
The weirdest one I found was a site that would only check to see if what you entered started with the correct password. So if your password was hunter2 and you tried hunter246, it would let you in.
Which means not only were they storing the password, but they had to go out of their way to use the wrong kind of string comparison.
USAA does this. I renentl learned that, when I updated my password a few years back to my personal standard number of characters, everything was good until someone mentioned this fuck-up in a thread. USAA only checks the first… 16? characters. I assume it just discards anything beyond that. Other users say that it warns and doesn’t let you enter more than that during password creation, but it/my pw mgr sure didn’t care, as I have a password several fold that limit. I took out a couple characters from my ‘set’ password, and it still logged in just fine. 16, just fine. 15, error.
Fucking wild.
The LM password hash (predecessor to NTLM) was calculated in two blocks of 7 characters from that truncated 14 characters. Which meant the rainbow table for that is much smaller than necessary and if your password is not 14 characters, then technically part of the hash is much easier to brute force, because the other missing characters are just padded with null.
